The present invention relates generally to pipe couplings, and more specifically to a self-aligning coupling assembly.
Making flexible fuel pipe connections using threaded fittings can be very difficult and time consuming when installing, for example, underground fuel piping systems at a service station. A quick connect type fitting is preferred when making these connections. In most prior art fitting configurations some axial movement of the pipes is required to properly join the pipes. Further, quick connect type fittings typically require their halves to be precisely aligned for making a connection. This alignment can be extremely difficult to achieve in the underground fuel pipe application.
In this regard, underground fuel pipe applications, fittings to be connected may be misaligned radially (see FIG. 1A) and/or angularly (see FIG. 1B). The fittings may be substantially fixed axially (see FIG. 1C showing an example of an axial gap for comparison). That is, the fittings may be attached to pipes that are fixed in the axial direction. For example, in a sump, one pipe may be buried underground and enter the sump through the sump wall, and a second pipe, to be attached to the first pipe, may be part of or attached to a T-fitting of a pipe opposite the first pipe. The T-fitting may further be attached to a horizontal pipe and a riser pipe extending upward from the fitting. Under such an arrangement both the first and second pipe would be substantially effectively fixed at their proximal ends and capable of little or no axial movement. Also, if the pipes are not on the exact same linear axis, even if only slightly offset, the pipes will be in radial and/or angular misalignment.
Further, for fuel applications, the requirements for a fitting may go beyond simply joining two pieces of pipe. Many quick connect fittings may be inappropriate and/or unsuccessful due to the number and nature of requirements placed on such a fitting, as there are several requirements and restrictions to consider that may eliminate many design options. For example, four such criteria for a fitting may be safety, reliability, low cost and ease of use. Safety is of course extremely important in the handling of flammable liquids.
Reliability of fuel connections, particularly in dispenser sumps, is important both for safety and economic reasons. Ideally, once installed, a fuel pipe and its connections can be forgotten. Servicing a fitting that develops a leak in service may require the removal of the dispenser, an expense in terms of labor and lost volume. To minimize these problems, fittings may require a design life set at 20 years or more without maintenance.
The cost of a fitting should also not exceed its functional value. If the product is to be successfully marketed, any costs must be justified to the customer. Ideally, any added cost will more be than made up by reliability, longevity and time savings.
Further, a fitting should be easy and intuitive to use. For example, quick connect fittings may be desirable over threaded fittings. By making fittings easy to use, it makes installation faster, saving both time and money. Also, because contractors unfamiliar with the product may use the fitting, the fitting""s purpose and manner of operation should be as clear as possible to the uninitiated to avoid accidents. To enhance ease of use, for example, the coupling should tolerate some radial and/or angular misalignment between the fittings when making a connection.
In addition to the above requirements, there may be four other design restrictions considered: size, pipe insert, pressure drop, and the coupling engagement. The size restriction may generally be compared to the length of the fitting. In order to provide room for other equipment, such at test boots in the sump, the fitting should be as short as possible. Ideally, a quick connect fitting would be no longer than the standard primary fitting or shorter, and the other fitting dimensions should be appropriately compact to accommodate space limitations, such as allowance for only two inches from center line for pipes on four inch centers.
Where one of the fittings is to be connected to a hose opposite the end connected to the other fitting, a further size restriction on the hose insert end of the fitting should be made for compatibility with current swaging machines. The insert may retain the same dimensions as current fittings from a snap ring shoulder of the fitting to the end of the insert to take advantage of a proven design and to save contractors from having to buy new machines or setup fixtures.
Pressure drop through the fitting should not be greater than present fittings. Increased pressure drop through the fittings can increase demands on fuel pumps. A significant increase in pressure drop through a station may necessitate larger pumps, which could offset any savings from quicker installation or reduced maintenance costs. Pressure drop is used as a marketing tool in the industry and high pressure drops could hurt a new products marketing.
An additional design criteria relates to the engagement between the fittings. Because some fittings to be connected may be axially fixed, it should be possible to disassemble the joint without relative axial movement of the fitting halves. This is sometimes referred to as xe2x80x9czero engagement.xe2x80x9d What is required is that any overlap or engagement of the fittings not interfere with radial movement of the fittings during disassembly. This allows, for example, one of the fittings to be removed and replaced without any movement of the other fitting.
A typical fitting may consist of an insert that is swaged outwardly against a pipe and a collar. A swivel nut may be trapped on the end of the insert by a shoulder, and a rubber gasket may provide a fuel tight seal. A shorter version may be made by eliminating the nut""s ability to retract axially past the seal face. Such a compact fitting allows more room for other components, such as a test boots inside a sump. Nonetheless, even disconnection of the compact fittings requires backing off of one side of the fitting from the other. This is not possible if the pipes are substantially axially fixed. As such, these previously available fittings find limited use.
As an example of a quick connect fitting, consider a KAMLOK(copyright) tee, shown in FIG. 8. The KAMLOK(copyright) tee 11 has a male nozzle fitting 12 and a female clamp fitting 14. The nozzle fitting 12 is inserted into the clamp fitting 14, the arms 16 rotate inwardly toward the body 15 of the clamp fitting 14. The arms lever or cam against the groove 13 of the nozzle 12 securing and sealing the nozzle 12 with the clamp fitting 14.
KAMLOK(copyright) fittings have several advantages. They are available in a variety of sizes and are also relatively inexpensive. However, KAMLOK(copyright)-type fittings do not always meet some key criteria and restrictions when applied, for example, in underground fuel pumping systems. First, the KAMLOK(copyright)-type fitting cannot correct misalignment of radially and/or angularly mating cylindrical surfaces, because it will tend to bind if the pipe is not well aligned. Secondly, the KAMLOK(copyright)-type fitting cannot be uncoupled without backing off one end of the fitting. In situations where substantially no axial movement is available, such a fitting has less success. Also of concern, the cam arms may vibrate loose over time, thereby potentially allowing a break in the seal and loss of containment.
In another example, push-to-connect fittings are commonly found connecting air hoses to pneumatic tools. The push-to-connect fittings are also available in a variety of sizes. These fittings create a seal by closely fitting two cylinders. As such, the push-to-connect fittings cannot tolerate misalignment. They also require that one end be backed off of the other for disengagement.
In yet another example of commercially available fittings, quarter turn, facial fittings go together very quickly and smoothly if aligned properly. One disadvantage of this fitting may be its relatively high cost. Besides the cost issue, there are several other deficiencies. Despite the open face, the overlap that allows the fitting to lock together similarly requires backing off of the mating parts to disconnect. Also, in order to couple, the faces have to be brought together in a parallel manner, and virtually no angular misalignment can be tolerated.
Installation of primary piping to elbows, tees, and other primary pipe fittings, is typically done by at least two people. In a conventional installation, for example, one person holds one pipe while another person aligns a fitting on one end of the pipe with another fitting to which the first pipe fitting will be received. With previously available arrangements, one person could not practically perform this installation, and conventional couplings and fittings cannot be joined if there is any appreciable misalignment between the fittings.
Where two pipes or two pipe fittings may each be fixed at opposite ends, axial movement of mating ends of the pipe will be minimal. The self-aligning assembly of the present invention should address and minimize the problems herein discussed and other problems which may become obvious to one skilled in the art.
The present invention relates to self-aligning coupling for mating a pair of axial arranged first and second flanged fittings. The self-aligning coupling comprises a first arm, a second arm, and a rotational assist mechanism. The rotational assist mechanism is adapted to mechanically synchronize the closing of the first and second arms relative to the flanged fittings to be connected. The rotational assist mechanism is further adapted to provide motion between the first arm and the second arm to receive and secure the second flanged fitting.
In another embodiment, a self-aligning assembly mates a pair of axial arranged first and second pipes. The second pipe has a flanged mating end and both pipes are substantially fixed opposite their mating ends. The self-aligning assembly comprises a flanged fitting and a self-aligning coupling. The flanged fitting is adapted to attach to the mating end of the first pipe. The self-aligning coupling has a first arm and a second arm. The first arm has a base end and a receiving end. The first arm base is pivotally connected adjacent to the flanged fitting when in use. The second arm has a base end and a receiving end. The second arm base is pivotally connected adjacent to the flanged fitting when in use. The second arm base engages the first arm base. The receiving ends of the arms uniformly move between an open position and a closed position to receive and secure the flange of the second pipe.
In yet another embodiment, a self-aligning coupling for mating a pair of corresponding flanged fittings comprises a pair of arms and a rotational synchronizer. The pair of arms are adapted for pivotal connection between opened and closed positions, and the arms at least partially defining a mating groove adapted to receive at least portions of a pair of flanged fittings to be coupled. The rotational synchronizer is provided adjacent the arms and is adapted to facilitate movement of the arms such that the flanged fittings can be received in the mating groove as the arms are effectively pivoted to the closed position.